<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>伪元素清除浮动</title>
    <style>
        /* 4-11,4-12 */
    </style>
</head>

<body>

</body>

</html>